I'm trying to guess here because your posts aren't very specific I'm not even sure what dates you mean? I presume you mean Joomla Articles Create / Modify/ Publish Dates?
Try this?
Admin ( back-end) / Content / Article Manager / Options / Articles
- Show Create Date = Hide
- Show Modify Date = Hide
- Show Publish Date = Hide
If this is what you mean, remember that Joomla works in a hierarchy method. There is Global Option, that apply to all sub categories as defined by the menus, but if those sub categories/menus have their own individual options which can be used to override the global options, if this is the case then they have to be changed individually. Basically try the above options, if there are any categories/menu options with dates still showing, more than likely they have their options set independently and they need to be changed to global or disabled, unless there is a bug.
Also the dates on Modules like News Show Pro GK4 are set by the individual modules so you probably have to either disable them individually or write / edit their main php to disable them all permanently (not recommened unless you know what you are doing.)
Components like K2 work in a similar way to Joomla Articles they'll be a Global option then individual categories will have their own individual override options.
Hope that helps, if you need more info / help, be specific about what exactly you want done, which dates you want to disable and where, show with screenshots, links etc, will be glad to have a look